A high accuracy is required in an oscillation frequency of a clock signal generation device applied to a wireless base station. For example, according to the W-CDMA scheme (3GPP TS25.141 (Non-Patent Document 1)), an accuracy of ±0.05 ppm is required.
To satisfy the accuracy, a wireless base station is proposed including: a voltage control oscillation section that outputs a clock signal having an oscillation frequency corresponding to a control voltage inputted to clock signal generation means of the wireless base station; a time information generation section that generates time information based on the clock signal outputted from the voltage control oscillation section; a time information comparison section that compares the time information generated by the time information generation section with reference time information; and a control voltage specifying section that specifies, to the voltage control oscillation section, a control voltage in accordance with a result of the comparison made by the time information comparison section (for example, see Patent Document 1). In the wireless base station, the time information generated based on the clock signal outputted from the voltage control oscillation section is compared with the reference time information that is not influenced by elapse of time, and the control voltage in accordance with the result of the comparison is specified to the voltage control oscillation section, and thereby the voltage control oscillation section corrects an oscillation frequency. This can keep the oscillation frequency of the clock signal simple and highly accurate.
Also proposed is a base station synchronization system including a plurality of base stations and a synchronization control device that makes a control for synchronizing the plurality of base stations with one another, the base station synchronization system being capable of suppressing a phase difference among master clocks of the base stations and accurately synchronizing the base stations with one another (for example, see Patent Document 2). In this system, the synchronization control device includes a control information generation section that generates synchronization control information for synchronizing the master clocks of the plurality of base stations with one another. The base station includes a master clock generation section that oscillates at a frequency corresponding to an inputted control voltage, and a control voltage correction section that corrects the control voltage inputted to the master clock generation section in accordance with the synchronization control information generated by the synchronization control device.